Eye tracking refers to the process of detecting the direction of a user's gaze, which may comprise detecting the angular orientation of the eye in three-dimensional space. Eye tracking may further comprise detecting the location of the eye (e.g., the center of the eye), the torsion (i.e., the roll of the eye about the pupillary axis) of the eye, the shape of the eye, the current focal distance of the eye, the dilation of the pupil, other features of the eye's state, or some combination thereof.
Eye tracking is an important feature for various systems used in artificial reality applications, e.g., head-mounted display (HMD) systems. Conventional eye tracking systems track features of the human eye and are typically limited by the quality of the optical path. These conventional systems do not provide sufficient accuracy needed for eye tracking in a HMD system.